The prior art radiochromic dosimeter is described in U.S. Pat. No. 4,377,751, issued Mar. 22, 1983. Related patents include U.S. Pat. No. 4,489,240, issued Dec. 18, 1984, and U.S. Pat. No. 4,602,425, issued Jul. 29, 1986.
The prior art radiochromic dosimeter includes a light transparent tubing filled with a transparent radiochromic liquid having a transparency which changes with the dose of ionizing radiation, the refractive index of the liquid being greater than the refractive index of the transparent tubing, an outer tubing opaque to ultraviolet light over the transparent tubing, the ends of the transparent tubing being enclosed and sealed to retain said liquid, and a clear ultraviolet absorbing coating over the enclosed ends to provide a shield against ambient ultraviolet light.
One problem with the prior art radiochromic dosimeter is that the absorbed dose is determined by comparing the color depth to a calibrated color wedge, so that there is sometimes a problem of obtaining an accurate dose measurement.